Respirator assembly

ABSTRACT

A respirator assembly e.g. for NBC protection is formed from two separate sub-assemblies. The first sub-assembly comprises a flexible hood (or other suitable headgear), a rigid mounting ring and a peripheral face seal. The second sub-assembly comprise a face plate with lens, oronasal mask and inlet and outlet valves, and is demountably attachable to the ring. The first sub-assembly can be worn on its own with the user breathing ambient air through the front end, the second sub-assembly being added if and when a hazard is encountered. The positioning of the face seal in the first sub-assembly means that a comfortable and reliable fit can be ensured when the sub-assembly is donned prior to a mission, but the user is relieved of the physiological burden of wearing the complete respirator unless and until protection is required.

The present invention relates to a respirator assembly for theprotection of personnel against contaminated or otherwise irrespirableenvironments. It has particular application for use by aircrew or othermilitary personnel who may be exposed to the risk of nuclear, biologicalor chemical (NBC) attack, but may be found to be of more generalapplication wherever breathing apparatus must be used, e.g. infirefighting or for industrial use where work must be performed inhazardous environments.

It is recognised that wearing a conventional respirator, whichencompasses the whole head or at least the face of the user to isolatethe nose, mouth and eyes from the external environment, imposes aconsiderable physiological burden on the user and severely limits theduration for which it can be worn without reducing the users ability toperform his mission effectively. It is therefore desirable to match theprotection to the hazard so that personnel are not required to wear fullrespirators for extended periods of time when standing by for action orwhen there may be a threat of a hazard but no actual hazard encountered.On the other hand, donning a conventional respirator, and in particularensuring that it is adequately sealed against the head to exclude theexternal environment, can be quite time-consuming, and it may be toolate to attempt to don when the hazard is actually encountered. In thecase of military combat aircrew who may require NBC protection, forexample, it is quite impractical for a conventional, respirator to bedonned in flight, meaning in effect that a decision must be made at thecommencement of a mission between wearing full protection for theduration of the mission—with the consequent and possibly unnecessaryphysiological burden which that implies—or no protection.

With the foregoing in mind, respirator assemblies have been proposedwhich can be worn in a partially disassembled, open face condition topermit free breathing of ambient air, and which are completed with aface piece supplied from a suitable source of breathing gas when theneed arises. For example U.S. Pat. No. 5,575,278 discloses an assemblycomprising a helmet with a flexible envelope extending downwards andsealing around the neck of the user, and a separate face piece which canbe attached to the helmet when required. In this arrangement isolationfrom the external environment depends on the neck seal which can beuncomfortable to wear and, being a component of the “permanent” part ofthe respirator, imposes this burden under both the partiallydisassembled and fully assembled conditions of use. U.S. Pat. No.5,078,130 discloses an assembly comprising a helmet with a face piecehinged to it which can be tilted up out of the way or pivoted down andpressed back against the helmet to complete the system as required. Theface piece carries a seal to seal around the periphery of the user'sface when pressed back against the helmet. Isolation from the externalenvironment and conservation of the breathing gas supply depends on thequality of this face seal and in practice it may not be possible toensure an adequate fit under all likely operational conditions andparticularly in haste.

The present invention seeks to provide a respirator assembly whichovercomes the above-indicated drawbacks of the prior art and accordinglyresides in an assembly comprising: a first sub-assembly adapted to beworn on the head and including sealing means adapted to form a sealaround the periphery of the user's face when worn; and a secondsub-assembly separable from the first sub-assembly but selectivelyco-operable therewith, the second sub-assembly comprising a face pieceadapted to co-operate with the first sub-assembly to define therewith afacial cavity bounded by said sealing means, inlet means connectable toa source of breathing gas for supply to the user and outlet means forthe exhaustion of exhaled gas from the user.

In use of the present invention the first sub-assembly can be donned atthe outset and the necessary time taken to ensure that its sealing meansis adequately sealed against the user's face before there is any risk ofexposure to the hazardous environment for which the respirator isintended. It can be worn in this condition to permit free breathing ofambient air, and with the face seal providing substantially bettercomfort in use than a constrictive neck seal, until the user is subjectto the risk of attack or otherwise required to enter the intendedhazardous environment, at which time the second sub-assembly is used tocomplete the system. An assembly according to the invention maytherefore achieve better comfort and/or reliability for the user thanthose disclosed in U.S. Pat. No. 5,575,278 and U.S. Pat. No. 5,078,130.

The first and second sub-assemblies may be completely separable wherebythe first sub-assembly can be worn alone, the second sub-assembly beingdemountably attachable to the first. Alternatively the secondsub-assembly may be hinged or otherwise articulated to the first.

In a preferred embodiment the first sub-assembly comprises headgearincluding a substantially rigid ring structure adapted to be juxtaposedto the user's face when the headgear is donned and from which saidsealing means extend to engage around the periphery of the user's face,the second sub-assembly being configured to be mounted to said ringstructure and secured thereto by releasable fastening means. In anyevent the first sub-assembly may comprise headgear in any appropriateform according to the operational requirements concerned, such as aflexible hood, an impact-resistant helmet, or simply a harnesssufficient to hold the rest of the assembly in position.

The respirator assembly may be used with any suitable source ofbreathing gas in accordance with the intended service. For example itmay be connected to a cylinder or other supply of compressed air oroxygen, or a filter canister selected for the hazard in question, withor without fan assistance, all in accordance with conventional practice.

The invention will now be more particularly described, by way ofexample, with reference to the accompanying drawings in which:—

FIGS. 1 and 2 are respective pictorial views of one preferred embodimentof a respirator assembly according to the invention shown in use in itspartially disassembled and fully assembled conditions; and

FIGS. 3 and 4 are respective schematic cross-sectional viewscorresponding to FIGS. 1 and 2.

The illustrated embodiment of the invention is in the form of arespirator hood assembly for providing protection against NBC hazards.It comprises a first, hood sub-assembly 1 shown donned on its own inFIGS. 1 and 3 and a second, face piece sub-assembly 2 shown attached tothe hood sub-assembly in FIGS. 2 and 4.

With reference to FIGS. 1 and 3, the sub-assembly 1 comprises a flexiblehead covering 3 which is also extended downwards over the shoulders ofthe user, and a substantially rigid profiled ring 4 attached to the headcovering so as to encircle the face of the user at an appropriatespacing when the head covering is donned. The ring 4 and covering 3 aresecured together around the whole of their mating edges and additionaladjustable ties 5 are provided between these elements to assist insupporting the ring 4 and the second sub-assembly 2 when the latter isadded. The ring 4 also carries a profiled elastomeric gasket 6 whichextends into sealing engagement around the periphery—brow, temples,cheeks and chin—of the user's face when the head covering is donned.

In operation the user can don the sub-assembly 1 as shown in FIGS. 1 and3, prior to a mission, and take the time to ensure that the gasket 6 isproperly and comfortably sealed against his face before there is anyrisk of exposure to the hazard. He can continue to wear the apparatus inthat condition into the mission, breathing ambient air through its openfront, until such time (if any) as respiratory protection is required,when the sub-assembly 2 can be added.

With reference to FIGS. 2 and 4, the sub-assembly 2 comprises a mouldedface plate 7 with inset lens 8 and a fitted air supply hose 9.Internally it carries an oronasal mask 10 (FIG. 4) with a soft sealingedge 10A to engage around the mouth and nose of the user when donned.The face piece sub-assembly 2 can be demountably attached to the hoodsub-assembly 1 and in the illustrated embodiment is retained by lugs(not shown) on the face plate 7 engaging in sockets 11 (FIG. 1) formedon the ring 4, one of which includes a manually-releasable latch 11A.The periphery of the face plate 7 is profiled to match the contour ofthe ring 4 and carries a seal 12 (FIG. 4) to ensure a gas-tightconnection between those elements when attached.

In the fully assembled condition of the respirator shown in FIG. 4 afacial cavity 13 is formed, bounded by the face plate 7 and gasket 6, inwhich the user's nose, mouth and eyes are isolated from the externalenvironment. The integrity of the peripheral face seal formed by thegasket 6 is crucial in this respect, and can be ensured by the carefuldonning of the sub-assembly 1 prior to a mission. The sub-assembly 2 canthereafter be donned quickly when required to complete the respiratorwithout compromising the integrity of the face seal. Within the facialcavity 13 a smaller subdivision 14 is formed by the interior of theoronasal mask bounded by the sealing edge 10A, but the integrity of thelatter is of secondary importance to the gasket 6.

In use of the respirator air is supplied via the hose 9 (FIG. 2) under aregulated positive pressure and enters the oronasal mask cavity 14through a one-way inlet valve 15 (FIG. 4). Exhaled air is vented toatmosphere through a one-way outlet valve 16. A stream of air is alsodirected through ports (not shown) in the mask 10 to pass over theinterior face of the lens 8 for demisting purposes, in accordance withknown practice.

The hood can be worn under an impact-resistant helmet if required andthe face piece sub-assembly 2 donned and doffed without removing thehelmet. The material of the head covering 3 can be selected to resistinward penetration of hostile airborne droplets and vapours butsufficiently air-permeable to permit evaporative cooling of the user'shead, (for example a microporous charcoal-impregnated cloth).

By virtue of the face seal formed by gasket 6 the assembly will besubstantially more comfortable to wear, both in the fully assembled andpartially disassembled conditions, than those respirator hoods whichdepend on the provision of a neck seal. The air-permeable head covering3 will also enhance user comfort. At the same time, by making the gasket6 part of the sub-assembly 1 which can be donned at leisure, theintegrity of the face seal can be more reliably ensured than in thoseassemblies where a face seal is applied only when a threat isencountered and likely in haste.

In a variant of the illustrated embodiment the lens 8 is provided in aseparate unit which can be sealingly attached to the face plate 7 orremoved from it if required. The remainder of the assembly can thereforebe worn without the lens unit to partially relieve the physiologicalburden on the user when there is no threat of contamination but e.g.when aircrew require to wear the mask 10 for hypoxia and/or Gprotection, the lens unit subsequently being added if a threat isencountered.

1. A respirator assembly comprising: a first sub-assembly adapted to beworn on the head and including a seal adapted to seal around theperiphery of the user's face when worn; and a second sub-assemblyseparable from the first sub-assembly but selectively co-operabletherewith, the second sub-assembly comprising a face piece adapted toco-operate with the first sub-assembly to define therewith a facialcavity bounded by said seal, an inlet means connectable to a source ofbreathing gas for supply to the user and an outlet means for theexhaustion of exhaled gas from the user.
 2. A respirator assemblyaccording to claim 1 wherein the first and second sub-assemblies arecompletely separable whereby the first sub-assembly can be worn alone,the second sub-assembly being demountably attachable to the firstsub-assembly.
 3. A respirator assembly according to claim 2 wherein thefirst sub-assembly comprises headgear including a substantially rigidring structure adapted to be juxtaposed to the user's face when theheadgear is donned and from which said seal extends to engage around theperiphery of the user's face, the second sub-assembly being configuredto be mounted to said ring structure and secured thereto by at least onereleasable fastener.
 4. A respirator assembly according to claim 1wherein the second sub-assembly is articulated to the firstsub-assembly.
 5. A respirator assembly according to claim 1 wherein thefirst sub-assembly comprises headgear in the form of a flexible hood ofair-permeable material.
 6. A respirator assembly according to claim 1wherein the second sub-assembly includes an oronasal mask to be disposedwithin said facial cavity.
 7. A respirator assembly according to claim 1wherein said face piece includes a demountable lens portion.